Because when a virus buds off, it takes part of the host's envelop. That makes it difficult to kill the virus without harming the host's cells. The virus is also constantly changing and evolving.

Define lytic:

destroys the cell

Define virulent:

immediately

Define temperate:

dormant

Define lysogeny:

period of latency

What is the family name for the ebola virus?

filoviridae

What is the family name for the flu?

Orthomyxoviridae

Common 20-sided polyhedral capsid:

icosehedron

Name the parts of a bacteriophage:

base

tail

sheath

nucleic acid

capsid

tail fibers

Name the three ways an animal virus can enter a cell?

direct penetration

membrane fusion

endocytosis

Scientists have determined that prion diseases are not caused by a type of slow virus because prions __________.

contain no nucleic acid

Which of the following types of genetic material is normally found only in certain types of viruses and not in cells?

dsRNA

HeLa cells are an example of a __________ cell culture.

continuous

Fertilized chicken eggs are useful for the culture of viruses for all of the following reasons EXCEPT __________.

they allow bacteriophages to become latent.

In the early 1900s, the virologist F. Peyton Rous discovered __________.

cancer-causing viruses

What is the advantage of lysogeny to the lambda phage?

the phage persists for generations in the bacterial chromosome

Each of the following features is common to both bacteriophage and animal virus infections EXCEPT __________.

uncoating

Name the common ways bacteriophages attach to the outer structures of a bacterial cell:

cell wall

flagella

pili

Negative-sense ssRNA viruses require which of the following enzymes for their replication?

RNA-dependent RNA transcriptase

Which of the following types of viruses replicates in the cell's nucleus?

herpes

Which of the following viruses creates a DNA intermediary molecule from the information in their RNA genomes?

retrovirus

The tail fibers of a bacteriophage are most useful during which of the following stages of the lytic replication cycle?

attachment

What is an infectious agent that does not contain any nucleic acid?

prion

What type of molecules are the capsid made out of?

proteins

Put the following terms in order, from simplest to most complex: a. virion b. capsomere c. capsid d. nucleocapsid

B,C,D,A

Most viral genomes are much smaller than the genomes of the cells they infect. Which of the following CANNOT be inferred from this statement?
a) Viral genomes can be enclosed in very small capsids.
b) Most viruses can infect only certain types of cells.
c) Viral genomes usually contain fewer genes than cellular genomes.
d) Viral genomes usually do not encode all of the enzymes or structures necessary for their replication.

B

The outermost layer of a virion fulfills which of the following functions of the virus?
a)protection
B)recognition and replication
c)protection and recognition
d)recognition
e)replication

C-protection and recognition

The majority of cases of infant diarrhea are caused by what kind of virus?

dsRNA viruses

Which of the following would be an appropriate mode of action for a new anticancer drug?

inactivation of an oncogene

Virus that infects plants:

viroids

Prion disease found in deer and elk:

Chronic Wasting Disease (CWD)

What condition in humans is linked to bovine spongiform encephalopathy?

vCJD

What are repressed cancer cells called?
What are they called when they are "turned on"?

protooncogene

onocogenes

How do viruses causes cancer?

They can activate protooncogene and/or inhibit the repressor gene from functioning properly.

A clear zone of phage infection in a bacterial lawn is ________.

phage

What is not a criteria for specific family classification of viruses?

lipid composition

A good bacteria that is affected by a temperate virus and then becomes virulent is defined as what?

lysogenic conversion

What method is used to count viruses?

plaque assay

Name the normal alpha helix protein:

cellular PrP

Name the misfolded beta sheet protein that causes disease and can only be destroyed by incineration:

Which of the following is NOT a direct mode of action of antimicrobial drugs?
a)inhibition of flagella formation
b)inhibition of nucleic acid synthesis
c)inhibition of protein synthesis
d)inhibition of cell wall synthesis

A

What is meant by selective toxicity?

Chemotherapeutic agents should act against the pathogen and not the host.

Why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug?